Conversion of olefinic hydrocarbons



Patented Aug. 5, 1941 2,251,580 CONVERSION or omrmrc mmnocmnons Robert F. Ruthrufl, Chicago, 111., assignor to Chempats Incorporated, a corporation of Delaware No Drawing.

12 Claims.

hydrocarbons, especially normally gaseous ole-.

pplication December 4,1939, Serial No. 307,446 7 finic hydrocarbons, to hydrocarbons of higher boiling points to produce a liquid product peculiarly suitable for use as a motor fuel or as a blending material for such fuel by reason of the high octane number and high octane-blending value of said liquid product.

- This'invention-has among its objects the use for the conversion of olefinic hydrocarbons to hydrocarbons of higher boiling points of a catalyst of high conversion efiiciency, said efliciency being maintained over long periods without liability to physical disintegration, and said catalyst after long use being capable of regeneration whereby its original activity is restored. Said catalyst is particularly adapted for use in the conversion of propylene and the butylenes which may be easily and rapidly polymerized with the production of liquid hydrocarbons boiling for the greater part within the usual motor fuel range.

For the conversion of olefinic hydrocarbons to hydrocarbons of higher boiling points by the polymerization thereof, the use of catalysts consisting of oxygen acids of pentavalent phosphorus, either as such or in the form of free acid adsorbed on or absorbed by solid bodies, has been suggested. Various salts of oxygen acids of pentavalent phosphorus have also been suggested as catalysts for the conversion of olefinic hydrocarbons to hydrocarbons of higher boilingpoints.

Among'the catalysts that have been suggested for effecting this conversion may be mentioned orthophosphoric acid, orthophosphoric acid promated by a heavy metal salt such as copper phosphate, orthophosphoric acid absorbed on carbon, mixtures of orthophosphoric acid and diatomaceous earth, mixtures of orthophosphoric acid with a copper phosphate and cadmium phosphate, and, finally, copper pyrophosphate. All of these. catalysts, while capable of effecting the conversion of olefinic hydrocarbons to hydrocarbons of higher boiling points, show various disadvantages. For

and expensive, it not impossible, to solve. The

" so-called solid phosphoric acids," consisting 'essentially of free phosphoric acid held in a matrix,

'also present corrosion problems unless care is dew point of water when water vapor is present in thereaction space and, in addition, such catalysts commonly disintegrate during use. Salts of oxygen acids of pentavalent phosphorus also commonly disintegrate during use and frequently present corrosionproblems. r 1

According to the present invention acatalyst is employed for the conversion of olefinic hy drocarbons to hydrocarbons of higher boiling points that is hard and not subject to physical disintegration and that furthermorepresents no corrosion problems. It .has been discovered in connection with this invention that superior re- I sults in the conversion of olefinic hydrocarbons to hydrocarbons of higher boiling points may be obtained by the use of a catalyst, the active ingredient in which ,consists of an adsorption com-' phosphate. As is well known to those skilled in the art, hydrous stannic oxide may be formed by a variety of methods, for example, by treating the solution of a stannate with acid, by theaddition of alkali to solutions of stannic salts, or by the action of nitric acid on tin. More specifically, it

has been found that the preparation of the catalyst ,for; use in the present invention may be ef- 'fected most conveniently by one of the methods outlined in the examples given below.

Exampte 1. -A solution is. made by dissolving, 200 g. sodium metastannate in 25:90 cc. water. The solution is then treated with 40 00. 85% orthophosphoric acid. The mixture is stirred and acid, for example concentrated nitric acid, is added slowly until the resulting solution is,

. strongly acid. The precipitate that forms is reexample, catalysts consisting of free oxygen acids of pentavalent phosphorus or such acids promoted by minor amounts of heavy metal salts present equipment corrosion problems that are diflicult reaction has moved by filtration, washed thoroughly, and dried. The final catalyst is obtained in the form of hard opal'escent lumps. U Example 2.-A mixture is made .containing 309 cc. concentrated nitric acid, 34 cc. orthophosphoric acid, and 691 cc.;water. The solution resulting is cooled, and '65 g. of tin in the form of foil is slowly added. After the resultant violent ided the 'mixture is boiled for an hour, following which the precipitate is re-' moved by filtration, washed thoroughly, and dried. The final catalyst is obtained in the form 01' white flakes easily formed into pills or other suitable shapes.

Example 3.-A mixture containing 3000 cc. wa-

ter, 19.5cc. concentrated hydrochloric acid, and;

75 cc. 85% phosphoric acid is brought to-a boil,.

and .a freshly prepared solution made by dissolving 150 g. stannic chloride (pentahydrate) in 150 cc. cold water is added with stirring. The resulting precipitate is removed by filtration and after washing is dried to give the catalyst in the form ofhard opalescent lumps.

While the scope of this invention is to be in no nic oxide. It has, been found that for maximum activity it is preferable to contact the phosphate with the freshly'formed oxide or hydrous oxide. If the oxide or hydrous oxide is allowed to age before being contacted with'the phosphate, adsorption of the latter is decreased so that catalysts of lowered initial activity and shorter active life result. It is believed that on ageing the individual particles of stannicoxide or hydrous stannic oxide. coalesce into larger aggregates having less adsorptive surface per unit weight than fresh material and hence exhibiting less adsorptive capacity. For this reason it is advisable to contact the phosphate with the adsorbent. when the latter is in the nascent or freshly formed state. It will be observed that this has been accomplished in the three examples given above. In Examples 1 and 2 the adsorbent is actually formed in the presence of the phosphate, while in Example 3 the stannic chloride solution used is freshly prepared, thus eliminating the growth of micelles of hydrous stannic oxphate, a precipitate is obtained having a high phosphoric oxide-stahnicoxide ratio. If, on the other hand, the stannic chloride solution is boiled for a short time or is allowed to stand for an appreciable period before being added to the dilute phosphate, the precipitates obtained have appreciably lower phosphoric oxlde-stannic oxide ratios.

In carrying out the present invention, the oleflnic hydrocarbons or the mixture of hydro- "carbons containing olefines is passed in contact with the catalyst held in a suitable chamber or reactor, the reaction gases being suitably preheated for the reaction.

As an example of.the results use ofthe catalyst of this invention, -data obtained on converting pure-isobutylene at atmospheric pressure in the presence of a catalyst'prepared according to Example 1 .will' be described. The oleiinic gas was preheated a tempera-v ture of 400 F. and was passed over 25 g. of the catalyst'at a rate of 0.3 cubic feet per hour. At

-' the end of a four-hour on-stream period 30 cc.

of liquid conversionproduct had been formed,

the rate of polymerization of oleflnic hydrocarbons is a function of the concentration of these materials, and accordingly, from economic considerations, such reactions are best run at superatmospheric pressure. Any suitable pressure may be used, but it is preferable to employ relatively high pressure, for example in excess of 150 pounds per square inch, although it is evident that the catalyst exhibits its polymerizing activity at atmospheric pressure and even exhibits its conversion ability at pressures below atmospheric. I y Y The optimum operating, temperature will depend somewhat upon the nature of the material under treatment and the product desired. For example, for the conversion of gaseous oleflnes such as propylene and the butylenes, a temperature in the range of approximately 300-450'1". is advantageous for effecting maximum conversion to a product containing essentially only motor fuel components. Under otherwise similar conditions, propylene requires'a higher temperature for a given conversion than the butylenes. Ethylene is scarcely affected by the catalyst of this invention. 'Only by operating under rather severe conditions, for example 1400 pounds pressure, a temperature of 450 F., and a flow rate of 5 cubic feet of charge per hour per pound ofcatalyst, is conversion of this olefine appreciable, and even when operating in this manner it is doubtful whether the conversions obtained are.

of commercial importance. However, it has been found that ethylene in the presence of higher oleflnes such *as propylene and the butyienes is converted at a much higher rate than when alone or diluted with paraflins. This is attriblength of time during which the charge remains in contact with the catalyst under its operating conditions, in other words, the space velocity-of the charge. In general, the charge is passed over the catalyst at a rate of 2 to 40 cubic feet of charge, measured asa gas at standard condi-' tions of temperature and pressure, per pound of catalyst per hour.

It is apparent that with any given charge the extent of reaction-and the character bf the prodobtained by the equivalent'to about 25%) conversion based on the charge. I w r As is wellfknown'to those skilled in the art,

not depend mainly on the operating pressure, the operating temperature, and the space velocity of the charge. It isobvious that many combinations of these variables will yield the desired amount and quality of product. As an example of satisfactory operating conditions, it may be (cited that on passing a charge containing 15% isobutylene,'35%'normal butylene and parafllns over the catalyst at a temperature of 350 F.,' a pressure of 1400 pounds per square inch. and at a rate of 20 cubic feet of charge per pound of catalyst per hour, practically all of the isobutylen'e is converted together with approximately -70% of the normal butenes present. In the present case higher conversion of the normal butenes was not deemed desirable. By decreasing either. or any combination of these variablestemperature, pressure, or time of contact-even olefines to higher boiling hydrocarbons within less than the quoted amount ofnormal butylenes reactspwhile conversion of isobutylene .remains practically constant. On the other hand, more complete polymerization of the normal butylenes results when the operating conditions are more severe. With a charge containing 30-35% propylene and 65-70% parafiins about 85% of the olefine is converted whenoperating at a temperature of 375 F., a pressure of 1400 pounds, and a space velocity of cubic feet of charge per pound of catalyst per hour.

If desired, the charge before passing to the reactor may be desulfurized, and gum-forming components may be removed by known means.

In the conversion reaction proper, the charge 'may, ifdesired, be passed through two or morev catalyst-filled reactors in series, and means may be provided for the recycling of unconverted gas back to the reactor or reactors. It has been found that the activity of the catalyst may be maintained for longer periods if the charge is saturated with water. visable to incorporate from 1 to 6% volume in the gaseous charge.

While the present'invention has been described in connection with details or specific examples steam by olefines to hydrocarbons of In some cases it is adthereof, it is not intended that these shall be regarded as limitations upon the scope of the invention except insofar as included in the accompanying claims.

'1 claim:

1. The process of converting olefinic hydrocarbons to hydrocarbons of higher boiling points by the polymerization thereof'comprising contacting said olefinic hydrocarbons at elevated temperatures with a catalyst comprising as an active ingredient an adsorption complex of phosphoric ,acid on hydrous stannic oxide.

' said mixture the motor fuel boiling range by the polymerization thereof comprising contacting said olefinic by the temperature, mixtures containing said olefineswith a catalyst comprising as an active ingredient an adsorption complex of phosphoric acid on hydrous stannic oxide.

9. The process of treating a mixture of hydrocarbons containing normal olefines and iso-olefines to efiect conversion of a portion thereof to hydrocarbons of higher boiling points by the polymerization thereof comprising contacting of hydrocarbons with a catalyst comprising as an active ingredient an adsorption complex of phosphoric acid on hydrous stannic oxide under conditions of temperature, pressure 2. The process of converting olefinic hydrocarbons to higher boiling hydrocarbons within the motor fuel boiling range by the polymerization thereof comprising contacting said oleflnic hydrocarbons at elevated temperatures with a catalyst comprising as an active ingredient an adsorption complex of phosphoric acid on hydrous stannic oxide. 3 v

3. The process of converting olefinic hydrocarbons to hydrocarbons of higher boiling points by the polymerization thereof comprising contacting, at elevated temperature mixtures containing olefinic hydrocarbons with a catalyst comprising as an active ingredient an adsorption complex of phosphoric acid on hydrous stannic oxide.

4. The process of converting olefinic hydrocarbons to higher boiling hydrocarbons within the 'motor fuel boiling range by the polymerization thereof comprising contacting, at elevated temperature, mixtures containing olefinic hydrocar- 1' bons with a catalyst comprising as anactiveingredien't an adsorption complex of phosphoric acid on hydrous stannic oxide. 5. The process of converting normally gaseous olefines to hydrocarbons of higher boiling points by the polymerization thereof comprising contacting said olefinic hydrocarbons at elevated temperatures with a catalyst comprising as an active ingradient an adsorption complex of phosphoric acid on hydrous stannic oxide.

.6. The process of converting normally gaseous and time suitable to e'ifect the preferential polymerization of said iso olefines.

10. The process of treating a mixture of hydrocarbo'ns containing normal olefines and isooleflnes to effect conversion of a portion thereof tovhydrocarbons of higher boiling points within the motor fuel boiling range by the polymerization thereofcomprising contacting said mixture I of hydrocarbons with a catalyst comprising as an active ingredient an adsorption complex of phosphoric acid on hydrous'stannic oxide under conditions of temperature, pressure and vtime suitable to effect preferential polymerization of said iso olefines.

- 11. The process of treating a mixture of hydrocarbons containing normal butylenes and isobutylene to effect the conversion of a portion thereof to hydrocarbons of higher boiling points by the polymerization thereof, comprisingcontacting said mixture of hydrocarbons with a catalyst comprising as an active ingredient an adsorption complex of phosphoric acid'on hydrous stannic oxide under conditions of temperature, pressure and time suitable to effect preferential polymerization of said isobutylene.

12. The process of treating a mixture of hydrocarbons containing normal butylenes and isobutylene to effect the conversion of a portion thereof to hydrocarbons of higher boiling point within the motor fuel boiling range by the polymerization thereof, comprising contacting said mixture of hydrocarbons with'a catalyst comprising as an active ingredient an adsorption complex of phosphoric acid on hydrous stannic oxide under conditions of temperature, pressure and time suitable to effect preferential polymerization of said isobutylene.

ROBERT 1'. Rumors. 

